Electrical resistance and method of making same



Dec. 2, 1941. w, BENNETT 2,264,285

ELECTRICAL RESISTANCE AND METHOD OF MAKING SAME Filed June 3, 1939 awed/L mm 3 119 ATT ORNEY. 7

Pat ented Dec. 2, 1941 ELECTRICAL aesrs'muoe AND METHOD or 1 I; G SAME I Willard H. Bennett, Newark, .Ohio, assignor, by

mesne assignments, to Owens-Coming Fiberglas Corporation, Toledo, Ohio, a corporation of Delaware Application June 3, 1939, Serial No. 277,286

12 Claims.

My invention relates broadly to electrical resistances and more particularly to a method of making high resistances for uses such as grid leaks and high voltage potential dividers.

One of the objects of my invention is to provide a method of preparing electrical resistances of extremely constant and permanent value.

Another object of my invention is to provide a method of inexpensively fabricating electrical resistors from glass fibers.

Still another object of my invention is to provide a method of treating glass fibers which contain metal for rendering the fibers electrically conducting and thereafter controlling the con- .ductivity thereof to term electrical resistors of permanent resistance value. v

A further object of my invention is to provide an improved construction of electrical resistance formed from treated glass fibers.

A still further object of my invention is to provide a construction of electrical resistance formed from a composite arrangement of treated and untreated glass fibers whose combined resistance determines the net resistance of the unit of the resistor thus formed.

Another object of my invention is to provide a construction of electrical resistance formed from glass fibers which are wholly embedded in insulating material with terminals electrically connected with opposite ends of the fibers for forming a constant resistance of high value.

Other and further objects of my invention reside in the method of treating glass fibers for fabricated electrical resistance units as set forth more fully inthe specification hereinafter following by reference to the accompanying drawing, in which:

- Figure 1 is a greatly enlarged longitudinal sectional view of a homogeneous drawn glass fiberhaving a metallic content; Fig. 2 is a similar view of the same glass fiber illustrated in Fig. 1 after the fiber has been heated in the atmosphere of hydrogen for subjecting the metallic content to a reduction process and rendering the metallic particles colloidal; Fig. 3 is a similar view of the glass fiber of Fig. 2 after it has been subjected to a further increase in temperature and the colloidal metallic particles have coalesced; Fig. 4 illustrates one method I employ for intertwining a plurality of strands of treated and untreated glass fibers for forming a composite resistance unit; Fig. 5 illustrates one form of resistance unit constructed in accordance with my invention; Fig. 6 is a cross sectional view taken on line 66 sistance unit constructed in accordance with my invention; Fig. 8 is a transverse sectional view taken on line 8-8 of Fig. '7; and Fig. 9 shows a diagrammatic circuit arrangement illustrating one application of the permanent electrical resistance of my invention.

My invention is directed to a method of manufacturing electrical resistors inexpensively on a quantity basis which will have the characteristic 2,133,235, of October 11, 1938, for Method and apparatus for making glass wool, and Games Slayter and John H. Thomas Patent 2,133,236,

of October 11, 1938, for Glass wool and method and apparatus for making same. Glass fibers containing metallic content are thus produced having physical characteristics somewhat analogous to the glass fibers illustrated in Games Slayter and John H. Thomas Patent 2,133,238, of October 11, 1938, for Glass fabric.

A strand of the glass fibers thus produced is 11- lustrated in Fig. 1 by reference character I as comprising a homogeneous body having an average diameter of about .0004 inch. The glass fibers are heat treated in an atmosphere of hydrogen with temperatures of the order of 550 C. and the fibers become electrically conducting by virtue of the liberation of colloidal particles as represented in Fig. 2. The colloidal particles of copper are illustrated under conditions of very large magnification at 2. These colloidal particles 2 do not touch each other but electrons are able to jump from particle to particle of copper in the treated strands Ia through the special distances 3 separating these particles provided the distances 3 are as small as the order of magnitude of the electron wave length. The rate of reduction of the fibers is a continuing one such that the rate of change of the quantity of reduced copper will decrease with the decrease in the remaining quantity of available reducible copper in chemical combination. This rate of reduction of copper will be in competition with a rate 0! coalescence of reduced copper and this rate of of Fig. 5; Fig. 7 illustrates another form of: recoalescence will increase with increase in temperin er wined treated; fi ers ndl i ihed at f; W; 147:? i 4:2'6 establish intimate electrical: cnnnectlcn tempermm z ni fixed by the chemical comwith: the canductive end caps :12 and: 4:; :The position as the glass; the diameter of: the; fiber; I :end: caps: 122i and M are. securedever the feuds and the character of: ithe: reducing atmosphere 50f; the? dielestric; :eoatingi l5: which :surrounds: or reducing: agentl; it can be shown in :at least th in rtwin d :fib rs and r me h ni ally sc sea: instances that the mana ers is to be ex,- uredai. l6? and: il i 3 i f I In; both: the fiormszillustratedz in Figs; 5 and l :risidity: is: imparted: to. :the: fiber strands by? the dielectric. coating which: intnnaeely surrounds the fiber: strands; 386 8358? Of ifihi intimate. interior: surface? :conta t 5 between :the: tubular zdielectrici eating and: the fiher =strandsi,. heat: generated in the :conducting nears readily dissipated :'=,'I'h coating; 2:2 and; 51:5 in Figs; 5 and, :7 respectively? is both an electrically insulating coating as well as a heat cenducting 'cjnatingif :Ellendency :to zdilc tric failure; through the formation thermal currents is substantially overcome; Since the: Eccndlictivity s; electrcnlczand the resistor would contain: nc zeleictroiytes whatsoever; :difii I culties due: to polarization and: electrolytic heat in? are absent In addition tothis; the only noise :present in this kind oi: a: ccnductorzwculd be the oh'ns'on: effect so that :this kind cf reslstor isideal I for grid leaks :in electron tube circuits; :1 have: illustrated one applicatlsn of a my: invention: to: an small separation of: the particles or copp'enis lost 2 electronitubei circuit :inwhichi the resistor is =ln-:- when thei colloidalipaifticles coalesce; as as results: I di'catecl at: 4; connected :in shunt with a condenser I the fiber: 111,: Fig. 3,' substantially as: good an: my 2% disposed between Wilt? circuit 2]: and; grid iifi ihsulatonas the nntreatednber'i i of:Fig. 1; :The oi the tubeindicated generally at 13 iBe'c'aus e of resistor of my: invennca i s thafi represented at: la 2 the rcionslaantand highrresistance' characteristic of: in Fig; i 2:: in; ;the process :of f my invention; the glass fiber rcsistaneaof imyzinventicng the re stage of the heat treatment may be determined: sistance finds many applications: in connection by the deeppurple coloroiithe fibers; charaeterwithielectaron tube circuits and: inconneciicn with istic of: colloidal 5 copper, which chan es: inho :a highivoltage nctential dividers: 5 2 i i i straw: ccldr characteristic oi: copper; under glass While :11 have described my invention certain; as ithe amount at icoalesced: copper grows: :pre off its preferred embodimentail; realize that mcdi deminant; i-i=i i-= i ;=:=;=fications:may=:be=made:and:Irdefirethatitbe =;=;=;=:=;=;=;=;=;=;=;=;=Aii;er- :treatmentzoi the fibers: asherein: =de+-= All understood; thatno :limitatlons zuponz my=in en+= z a scribed, I may intertwine a multiplicity of such tion are intended other than may be imposed by fibers in a yarn which I have indicated generally the scope of the appended claims. in Fig. 4. The treated glass fibers are indi- What I claim as new and desire to secure by cated at 4 intertwined with glass fibers l which Letters Patent of the United States is as follows: contain little or no copper '01 other reducible 1. The method of making electrical resistances metal. The aggregate resistance of a multiplicwhich comprises drawing fibers from molten glass ity of intertwined fiber strands depends upon the of a composition including a conductive metal in conductivity of the individual fiber strands and chemical combination, and heat treating the the multiplicity of strands may be mounted in fibers in a reducing atmosphere and at a suma suitable carrier to form an element of an elecciently high temperature to produce a colloidal trical circuit. dispersion of metallic particles in the glass, the

Instead of intertwining a multiplicity of treated fibers with said colloidal dispersion thereinhavand untreated fiber strands, I may directly mount ing semi-conductive properties characteristic of fiber strands after heat treatment as illustrated an electrical resistance. in Fig. 5. The thread or fiber 4 is embedded in 2. The method of making electrical resistances an insulating body 22 such as, for example, a which comprises drawing fibers from molten glass plastic or a varnish or water glass or any other of a. composition including copper in chemical insulating material. The coating may be concombination, and heating the fibers in a reducing stituted by a glass tubing through which the fiber atmosphere and at a sulficlently high temperature 4 is drawn or the sheath :2 may be glass molded 0a to prod e the d p p rple color r stic f directly about and in intimate contact with the colloidal copper in the fibers, the fibers with the glass fiber l. The ends of the glass fiber 4 extend colloidal copper therein having semi-conductive beyond the ends of the insulated coating 22 as properties characteristic of an electrical resistindicated at 6 and 1. Around the ends 8 and I, ance. the conducting terminal caps 8 and 8 are formed. 3. The method of making electrical resistances The conducting terminal caps 8 and 9 may be cast which comprises drawing fibers from molten glass directly about the extended ends 8 and 1 of the of a composition including a conductive metal in glass fiber forming an intimate electrical connecchemical combination, and heating the fibers in a lion therewith. A tight mechanical connection reducing atmosphere and at temperatures of the may be established between the ends of the inorder of 550 C. for producing submicroscoplc sulated sheath 22 and the conducting terminal metallic bodies throughout the fibers with spaces caps 8 and 9 at I 8 and I I. therebetween of the order of magnitude of the In Fig. 7 I have shown the manner of embedwave length of the electron, whereby electrons ding an intertwined resistor of the construction may be transferred between said bodies, the fibers illustratedin Fig. 4. In this arrangement the with said submicroscoplc bodies therein having crease with :eon'tinued reduction at any given fixed ieleivaredi temperature; 5 The? value: of: ;;t :1i maximum obtainable conduciiviiy will be differ;- ent for difierent reducing: temperatures for, any

,givEmgmsS I phera :If the ternpe prolcnge'd over :the: temperature or: the time for producing: the greatest degree cf conductivity? in the fibers; colloidal: particles iofi clipper; :ecr-

esce; forming: larger globules of copper; in the: g la ss :and the ccndirctivity iof the fibers: Iiisaplnears; =F1he' internal structure. or :the: fibers :at this advanced stage of heal: treatment repre.- sented in Fig.5 3; where :th'e fiber? lb is shown with globules 2 of copper separated by spaces: 3",: It is; seen. :by comparison oi; Figs; 2 and :3 that :the characteristici of the =cc1loidal= tcrm; =Figfl; 2, by which conductivity; is obtained; that is tha :very

semi-conductive properties characteristic of an electrical resistance.

4. The method of making electrical resistances which comprises drawing fibers from molten glass of a composition including a conductive metal in chemical combination, and heating the fibers in a reducing atmosphere, at such temperatures and for such duration as will cause the metal to be reduced and reduced metal atoms to coalesce into submicroscopic metallic aggregates spaced by distances of the order of magnitude of the wave length of the electron, the heat treatment being terminated before said submicroscopic aggregates can grow to such an extent that the distances therebetween substantially exceed the Wave length of the electron, the treated glass fibers having semi-conductive properties characteristic of an electrical resistance.

5. The method of making electrical resistances which comprises drawing fibers from molten glass of a composition including a conductive metal in chemical combination, and heating the fibers in a reducing atmosphere, at such temperatures and for such duration that the fibers assume a color characteristic of the colloidal state of the metal in the glass compound, the heat treatment being terminated before the fibers can assume a color characteristic of the free metal, the fibers with the colloidal metal therein having semi-conductive properties characteristic of an electrical resistance.

6. An electrical resistance comprising a fiber of glass containing a colloidal suspension of metal of such density that the distances between the colloidal particles are of the order of magnitude of the wave length of the electron, whereby electrons may be transferred between said colloidal particles, said fiber having semi-conductive properties due to the transfer of electrons between the colloidal particles in the glass under the influence of an electromotive force applied at the ends of said fiber.

'7. As a product of manufacture, a fibrous glass body having colloidal metal dispersed therein to provide a semi-conductive electrical characteristic, an adherent covering of insulation material on said glass body for protecting said body from contact and breakage, and terminals for said body connected with the ends thereof and engaging said covering in sealing relation.

8. An electrical resistance which comprises a multiplicity of electrically semi-conductive and electrically non-conductive glass fiber strands intertwined one with another, the glass of said semi-conductive strands having colloidal metal dispersed therein to provide the desired electrical characteristic, a dielectric envelope for imparting rigidity to said fiber strands, and means for establishing electrical connection with opposite ends of said semi-conductive fiber strands.

9. An electrical resistance comprising a multiplicity of intertwined electrically semi-conductive and electrically non-conductive glass fiber strands, the glass of said semi-conductive strands having colloidal metal dispersed therein to provide the desired electrical characteristic, a dielectric sheath extending in intimate relation to said intertwined glass fiber strands, and terminating short of the ends of said glass fiber strands, means engaging opposite ends of said dielectric sheath and establishing electrical connection with the ends of said glass fiber strands for employing said semi-conductive glass fiber strands as electrical resistances.

10. The method of making electrical resistances from glass fibers having a high metallic chemical content which includes heat treating the fibers in a reducing atmosphere and at a sufficiently high temperature to produce a colloidal dispersion of metallic particles in glass, the fibers with said colloidal dispersion therein having semi-conductive properties characteristic of an electrical resistance.

11. As a product of manufacture, a fibrous body of glass containing colloidal copper dispersed therein, the colloidal particles of copper being spaced distances of the order of magnitude of the wave length of the electron, whereby electrons may be transferred between said colloidal particles, providing a semi-conductive electrical characteristic for said body.

12. An electrical resistance which comprises a plurality of electrically semi-conductive glass fibers parallelly related, the glass of said semiconductive fibers having colloidal metal dispersed therein to provide the desired electrical characteristic, and terminals secured to opposite ends of said fibers for establishing electrical connection with said opposite ends.

WILLARD H. BENNETT. 

